Isolation, identification and quantitation of hydroxycinnamic acid conjugates, potential platform chemicals, in the leaves and stems of Miscanthus×giganteus using LC–ESI-MS

Abstract

Miscanthus×giganteus is a source of platform chemicals and bioethanol through fermentation. Cinnamates in leaves and stems were analysed by LC-ESI-MS(n). Free phenols were extracted and separated chromatographically. More than 20 hydroxycinnamates were identified by UV and LC-ESI-MS(n). Comparative LC-MS studies on the leaf extract showed isomers of O-caffeoylquinic acid (3-CQA, 4-CQA and 5-CQA), O-feruloylquinic acid (3-FQA, 4-FQA and 5-FQA) and para-coumaroylquinic acid (3-pCoQA and 5-pCoQA). Excepting 3-pCoQA, all were also detected in stem. 5-CQA dominated in leaf; a mandelonitrile-caffeoylquinic acid dominated in stem. Three minor leaf components were distinguished by fragmentation patterns in a targetted MS(2) experiment as dicaffeoylquinic acid isomers. Others (M(r) 516) were tentatively identified as hexosylcaffeoyl-quinates. Three positional isomers of O-caffeoylshikimic acid were minor components. p-Hydroxybenzaldehyde was also a major component in stem. This is the first report of the hydroxycinnamic acid profile of leaves and stems of M.×giganteus.

Screening for potential co-products in a Miscanthus sinensis mapping family by liquid chromatography with mass spectrometry detection

“…Data are presented in Table 2. 5-Caffeoylquinic acid was the most abundant hydroxycinnamate in all tissues examined; this was also true of the hybrid M. × giganteus (Parveen et al, 2011) parent plants.…”

“…been reported in a range of monocots (Parveen et al, 2010). Geometrical isomers (cis / trans) were evident based on photoirradiation experiments resulting in photoisomerisation (Parveen et al, 2011).…”

“…LCelectrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS) has been used to characterise and quantify rapidly hydroxycinnamic acid conjugates and flavonoids in a wide range of plants (Parveen et al, 2011;Valls et al, 2009;Clifford et al, 2006).…”

“…Analysis by HPLC was carried out as reported previously (Parveen et al, 2011(Parveen et al, , 2008. Corporation, USA).…”

“…Plants produce a wide array of mono-and poly-phenols, with roles in strengthening cell walls, UV protection, stress tolerance and resistance to pathogens (Parveen et al, 2011(Parveen et al, , 2010. These include hydroxycinnamic acid conjugates and flavonoids from the phenylpropanoid and shikimate pathways and have antioxidant and UV-absorbing…”